Loss of biodiversity

Biodiversity is affected through a variety of means. Landscaping with non-native plants that adapt well to a new climate, for example, can allow the non-native plant to spread at the expense of native plants. Ranching has led to problems in places such as Death Valley, a fragile ecosystem where hardy grasses that were originally introduced into neighboring ranges for sheep ranchers, have invaded and outcompeted indigenous and rare species within Death Valley itself.

Section of Evolution and Ecology, University of California, Davis 95616, USA.

The spread of exotic species and climate change are among the most serious global environmental threats. Each independently causes considerable ecological damage, yet few data are available to assess whether changing climate might facilitate invasions by favoring introduced over native species. Here, we compare our long-term record of weekly sessile marine invertebrate recruitment with interannual variation in water temperature to assess the likely effect of climate change on the success and spread of introduced species. For the three most abundant introduced species of ascidian (sea squirt), the timing of the initiation of recruitment was strongly negatively correlated with winter water temperature, indicating that invaders arrived earlier in the season in years with warmer winters. Total recruitment of introduced species during the following summer also was positively correlated with winter water temperature. In contrast, the magnitude of native ascidian recruitment was negatively correlated with winter temperature (more recruitment in colder years) and the timing of native recruitment was unaffected. In manipulative laboratory experiments, two introduced compound ascidians grew faster than a native species, but only at temperatures near the maximum observed in summer. These data suggest that the greatest effects of climate change on biotic communities may be due to changing maximum and minimum temperatures rather than annual means. By giving introduced species an earlier start, and increasing the magnitude of their growth and recruitment relative to natives, global warming may facilitate a shift to dominance by nonnative species, accelerating the homogenization of the global biota.

In other words, warmer springs not only lengthens the growing season for farmers, but also allows some non-indigenous species (sea squirts, in this instance) to outcompete native species. The mean temperature throughout the year is of less importance than whether temperature is warmer, in the winters.

Is competition of native and migrating intruders something new?
Isn't that the evolution process ongoing for almost a gig-year?
Is ocean "warming" triggered by atmospheric climate change or by long term oceanic oscillations?
Is atmospheric climate change causing long term oceanic oscillations or is it the other way around?
Is the suggestion that fossil fuel burning has caused this phenomenon and that we could prevent more of it from happening if we cut back a few %%?

Are there any cases in the past of climate changes and loss of bio diversity? On the other hand there has been an abrupt climate warming that caused more biodiversity, the Palaeocene Eocene Thermal Maximum. The jump can be seen here, in figure one just after the major marine foraminifera extinction of the PETM boundary itself around 55 Mya

At least using human intelligence and worldwide contacts it will be possible to protect these genetic lines by using various climate zones across the globe to transfer species to.

As PattyLou says "The causes are broader than climate change"(CC). However CC is still a major issue and should not be overlooked. In highly urbanized areas such as Western Europe a problem that wildlife faces in response to changing climate is the lack of corridors along which to migrate in response to changing climate. And as is already being seen in the South East UK, declining river levels and a lower water table as a result of human demands for water place wildlife in direct competition with humans. There are some urban winners, foxes, pigeons etc. But they are but a small part of the pre-existing bio-diversity. Furthermore the rate of climate change is and will further, compound the problems urbanization and land-use change in itself presents.

Whilst it has to be recognised that in places such as the UK we already have an artificial environment, even places of 'natural' beauty like the Lake District would forest were it not for agriculture (sheep). I think that the pace of change we now face is a significant concern.

So what you are doing is, in my view, crucial to try to keep at least a section of the current biodiversity intact. Despite the pace of change, by managing the movement of species in a considered manner we may be able to mitigate impacts on at least a part of the genetic heritage.

Hi Cobby
You should see what we have done to the majestic Colorado river, which use to teem with wildlife. The once rich delta in Mexico, is dead, fuled only by salt and pesticide laced run off. Many species of plants and wild life are just gone.
The demand has exceeded the rivers capacity to support the southwest.

In the UK the South East's water issue is great, caused by increasing demand compounded by a combination of reduced and changed precipitation.

However rivers in the North, such as the Irwell in Manchester are now reportedly cleaner than they have been since the start of the industrial revolution. So all is not negative. The problem being that human demand for water is not really a negotiable factor - more people consistently means more demand. Pollution however can not only be addressed by greater regulation, but may be dealt with by drives fo greater efficiency, particularly in farming. The latter could be one good spin off from GM food production (although I suspect you may see greater downsides than the gain of a reductiion in pesticide an fertiliser usage).

If we were to destroy 90% of the species on the planet, and if most of those are the larger animals, the remaining 10% would have more resources to allow them to speciate.

I'm not saying this well. It's part of evolution, most explosions in speciation occur after a mass extinction. So we had something of a dinosaur planet, and that crashed, and now we have something of a mammal planet.

It was told to me by my Grandfather that we should look at the earth as a species unique to its self. The earth has symbiont relationships with us. But if its out of balance, the earth will do what is necessary to survive.

It was told to me by my Grandfather that we should look at the earth as a species unique to its self. The earth has symbiont relationships with us. But if its out of balance, the earth will do what is necessary to survive.

I appreciate the metaphor and there is wisdom in it. But as far as we know
the earth does not act with a purpose of it's own. After all, its a ball of dirt.
The myriad animals and plants that make up the living portion of the
earth would be fine on any planet that had the right climate including
sunlight.

For the purposes of science, human activities are like that of any other
animal except that it might be (somewhat) under our control. Nevertheless
I don't think the earth will "come after us" if we trash it. We will have come
after ourselves.

Pattylou, then as you have described it the loss of biodiversity is a naturally
self-correcting phenomenon.

yes, but selfcorrecting in million year time scales. it took 50 million years for biodiversity to stabilize after permian mass extinction. want to wait that long? among the 90% species that will die out in the next major extinction event(when it happens) do include homo sapiens sapiens on the list.

Is competition of native and migrating intruders something new?
Isn't that the evolution process ongoing for almost a gig-year?

The practical matter at hand seems to be (1) is the current rate of invasion/extinction higher than normal? (i.e., are we seeing the beginning of the "sixth extinction"?) and (2) is a dramatic shift in the ecosystem (local/global) good or bad for humans?